7500 HARDESON RD Geotech Report 2022-10-25

Geotechnical Engineering Report SSGC I-iardeson Road Retail Everett,Washington ' SSGC Project No. 18072 September 18,2018. On-Grade Floor Slabs On-grade floor slabs should be placed on firm native soils or structural fill prepared as described in this ' report. We recommend a modulus subgrade reaction of 225 pounds per square inch per inch (psi/in) for native soil or compacted granular structural fill over native soil. ' We recommend a capillary break is provided between the prepared subgrade and bottom of slab. Capillary break material should be a minimum of 4 inches thick and consist of compacted clean, free- draining, well graded course sand and gravel. The capillary break material should contain less than 5 percent fines, based on that soil fraction passing the U.S. No. 4 sieve. Alternatively, a clean angular gravel such as No. 7 aggregate per Section 9-03.1(4) C of the 2016 WSDOT (M41-10) manual could be used for this purpose. We recommend positive separations and/or isolation joints are provided between slabs and foundations, and columns or utility lines to allow independent movement where needed. Backfill in interior trenches ' beneath slabs should be compacted in accordance with recommendations presented in this report. A vapor retarder should be considered beneath concrete slabs that will be covered with moisture sensitive or impervious coverings (such as tile, wood. etc.). or when the slab will support equipment or stored materials sensitive to moisture. We recommend the slab designer refer to ACI 302 and/or ACI 360 for procedures and limitations regarding the use and placement of vapor retarders. Seismic Considerations Seismic parameters and values in Table 2 are recommended based on the 2015 International Building Code(IBC). ' Table 2. Seismic Parameters PARAMETER VALUE 2015 International Building Code(IBC) Site Classification' S,Spectral Acceleration for a Short Period 1.473 ' Si Spectral Acceleration for a 1-Second Period 0.551g Fa Site Coefficient for a Short Period 1.00 ' F,Site Coefficient for a I-Second Period 1.5 Note:In general accordance with the 20I5 International Building Code. Section 1613.3.2 for risk categories 1.11111. IBC Site Class is based on the estimated characteristics of the upper 100 feet of the subsurface profile. S.Si.F.and F,values based on the USGS US Seismic Design Maps website using referenced site latitude and longitude. I 8